A combined peritumoral and intratumoral signature of HER2-E on pretreatment MRI was found to be significantly associated with pCR, consistent with the HER2-E subgroup’s superior response to HER2-targeted therapy compared with other HER2+ breast cancers.4 This association was supported in 2 independent validation cohorts from different institutions: one with high heterogeneity (PRC1: mixed magnetic strengths and scanner manufacturers, multiple treatment regimens, variability in voxel size) and the other with homogeneous treatment and MRI acquisition protocols. This evidence concerns the gene ERBB2 and breast cancer.